Metal tipping for propellers



Feb. 24, .1931. F: CHARAVAY METAL TIPPlNG FOR PROPELLEHS Fig.6.

Filed June 4. '1929 Q 1 B! Q ATTORN/i) propellers.

Patented 24, 1931 UNITED STATES PATENT OFFICE FREDERICK CHARAVAY, OFIIQU'A, OHIO, ASSIGNOR OI ONE-HALF TO HARTZELL INDUSTRIES INC., OFPIQUA, OHIO, A. CORPORATION 01 OHIO METAL TIIPING FOR PROPELLEBSApplication filed June .4,

This invention relates to new and useful improvements in metal tippingforairplane It is the principal object of my invention to provide acombination hard and soft metal tip for wood airplane propellers. A hardmetal such as Monel, may be easily punched, but it is drilled withdifiiculty. However, when the hard metal is used only on the face of thepropeller, where it is most needed, and a soft metal such as brass isemployed on the back side where there is little wear, the two metals maybe easily riveted to the thin propeller tip by first punching the hardmetal. The drill is then started through the latter, the propeller tipand the brass piece on its back side to provide holes to receive therivets.

Such a propeller tip is armored with the hard metalon its face where itstrikes weeds, stones and cinders, and with soft metal on its rear sidewhere there is little wear. Furthermore, economy of manufacture ispromoted by the use of soft metal with the hard, since the latter ismore expensive, and when used on both sides of the tip increases thecost of its production.

It is another object of my invention to provide a soft metal strip, suchas brass, along the leading edge of the rear portion of the woodpropeller, with a serrated section of hard metal along that portion ofthe leading edge of the propeller where its velocity is high and whereit is more exposed to the ele-' ments such as rain. 1

Other important and incidental objects will be brought out in thefollowing specification and particularly set forth in the subjoinedclaims.

In the accompan ing drawings illustrating my invention, igure 1 is aview of the rear side of my improved propeller. Figure 2 is a crosssectional View takenthrough the .same on the line 22 of Figure 1,showing 1929. Serial no. 368,258.

propeller on the line 44 of Figure 1, show- 1ng' how the serrated hardmetal strip is screwed over the middle front art of the leading edge ofthe propeller. igure 5 is a plan view of the hard metal strip attachedto the propeller. And Figure 6 is a plan view of the soft metal pieceattached to the propeller tip.

Referring to the accompanying drawings for a detailed description of myinvention, the numeral 1 desi nates one end of a wood propeller ofaerofoll section. The propeller is tipped with two metal strips, one ofhard metal add the other of soft metal, to reduce the cost of productionwithout impairing the efliciency 0 the propeller.

Referring to Figure 5, the numeral 2 designates a metal blank preferablyof Monel metal, with a wide tapered head portion 3 and an elongated,serrated tail-portion 4. In Figure 6 there is shown a blank 5 of softmetal, preferably brass.

The brass strip 5 is first applied to the rear face of the pro eller tipand bent over its leading edge, a or which the Monel metal strip 2 isapplied to the front face of said tip. The head portion 3 of the Monelmetal strip 2 isthen lapped over the brass strip 5 and soldered to thelatter as shown ures 1, 2 and 3.

Holes are punched in the head portion 3 of the Monel metal strip'2 afterwhich a drill is started through those holes, the thin propeller tip andthe brass strip 5. Rivets 6 are then inserted in said holes and theirheads soldered over. (See Figures 1, 2 and 3.)

Through the holes 7 1n the tail portion 4 of the Monel metal strip 2,screws 8 are inserted for passage into the propeller after said strip isbent over its leading edge.

Over the leading edge of the propeller 1, behind the Monel metal strip2, a brass strip 9 is secured by screws. These screws, as well in Figasthe. screws 8, are soldered over to make the surface of the brass andMonel metal strips uniformly smooth.

. The application of the Monel metal to the face of the propeller tipand to that portion of its leading edge immediately behind the tipreinforces it for the severe wear to which it is subjected throughcontact with stones, weeds and cinders and exposure to rain. The rearface of the tip, not being ex osed so much to the wearin action just reerred to, is covered with a so ter and cheaper metal such as brass whichmay also be easily drilled.

The tail portion 4 ofthe Monel strip 2, which is serrated to preventbuckling when the propeller vibrates, protects the leading edge of thelatter at the points where its velocity is high. 7 Behind these, points,the leading edge is covered by the softer and cheaper strip 9. y

The propeller end (not shown(; on the other side of the hub is tipped ancovered at its leadingedge in the same manner as the end which has justbeen described.

, Having described my invention, I claim:

- 1. A wood propeller of aerofoil section, having a combination hardmetal and soft metal tip at each end.

2. A wood propeller of aerofoil section, having a combination hard metaland soft metal tip at each end, the hard metal being on the face side ofthe propeller, and lapping over the soft metal which is on the back sideof said tip.

3. A propeller comprising a wood unit of aerofoil section, a brass stripapplied to the back face of each tip of said propeller and bent over itsleading edge, and a nickel and copper alloy strip applied to the frontface of each tip, and lapped over the brass strip.

4. A propeller comprising a wood unit of aerofoil section, a soft metalstrip applied to the back face of each tip of said propeller, a hardmetal strip applied to the front face of each tip and lapped over thesoft metal strip,

1 and rivets passing through the hard metal strip, propeller and softmetal strips for se- 8. In a propeller blade, a tipping thereforcomprising a continuous strip of hard metal embracing a part of one edgeand the face side of the ti of the blade, and a continuous strip of a sometal embracing another part of the same edge of the blade, one end ofone strip' contacting an end of the other strip.

9. In a propeller blade, a protector therefor comprising a strip ofnickel and copper alloy, and a strip of brass covering a leading edge ofthe blade, the strip of nickel and copper alloy covering that part ofthe blade most subject to wean 10. In a propeller blade, a protectortherefor comprising a strip of nickel and copper alloy covering aleading edge and the face side of the tip of the blade.

11. In a propeller blade, a protector therefor comprising a strip ofnickel and copper alloy covering a leading edge and the face side of thetip of the blade, and a brass strip covering the back side of the tip.

12. In a propeller blade, a protector therefor comprising a strip ofbrass covering the back side of the tip of the blade, and a strip ofnickel and copper alloy covering a leading edge and the face side of thetip and overlapping the edges of the strip of brass.

In testimony whereof I have hereunto set my hand this 31st day of May,1929.

FREDERICK CHARAVAY.

curing said metal strips to their respective propeller tips.

5. A propeller comprising a wood unit of aerofoil section a soft metalstrip secured to the back face 0 its tip, a hard metal strip secured tothe front face of said tip, and lapped 'over its leading edge, andhaving a serrated portionprojecting over the leading edge a shortdistance behind said tip, and a soft metal strip secured over theleading edge of said propeller behind the hard metal strip.

6. In a propeller blade, a tipping therefor comprising a continuousstrip of metal embracing a part of one ed e of the blade, and acontinuous strip of a di erent metal embracing another part of the sameedge of the blade, one end of one strip contacting an end of the otherstrip.

7 In a propeller blade, a tipping-therefor comprising a continuous stripof hard metal embracing a part of one edgte of the blade, and

a continuous strip of a so ing another part of the same edge of theblade, one end of one strip contacting an end of the other strip.

er metal embracits

